The group which killed American journalist James Foley have many more hostages

Up to 20 Western hostages are being held by the jihadi group that beheaded James Foley.

As well as the journalist Steven Sotloff, who was threatened with beheading by the same man who murdered Foley, Islamic State in Iraq and the Levant (Isil) is holding a number of aid workers, thought to include Vanessa Marzullo, 21, and Greta Ramelli, 20, both Italian.

Three aid workers employed by the International Committee of the Red Cross (ICRC) are also being held hostage after they were abducted last October.

As fears grew that Isil could make good on its threat to murder more hostages, families of those being held defended their loved ones’ decisions to travel to Syria.

Ms Ramelli’s mother, Antonella, said her daughter had been determined from an early age to look after others, starting by helping out in a retirement home when she was 12.

Responding to suggestions that she should not have allowed her daughter to travel to Syria, Mrs Ramelli said: “When you hear your daughter say 'Mamma, in that country they are killing children, I must go and help,’ what can you say?”

“Can you go back on all the teaching and the values you have tried to instill for a lifetime?” she told Prealpina, an Italian newspaper. “Can you change your daughter, who has these values and has strong ideals about solidarity and human empathy?”

The two women went missing near Aleppo in Syria at the beginning of this month. On Thursday the Italian foreign office declined to comment on whether they were now in the hands of Isil.

The Red Cross has not released details of the nationality, gender or age of their aid workers currently being held hostage. The three were among a group of seven who were kidnapped, four of whom were released shortly afterwards.

A spokesman for the charity said: “Intensive efforts are ongoing behind the scenes to secure the release of the remaining three colleagues, through the ICRC’s broad network on the ground.

"We cannot provide details about this for the sake of the ongoing safety of our colleagues still abducted.”

Former hostages who had been held with Foley described how he had been singled out for beatings because he was an American.

Didier Francois, a 53-year-old reporter with the French radio station Europe 1, said Mr Foley was tortured after his captors found pictures on his computer of his brother, who works for the US Air Force.

Foley was subjected to mock executions, including one in which he was “crucified against a wall”.

Paying tribute to the American, Mr Francois said: “He was an extraordinary guy — a companion in imprisonment who was very agreeable, very solid.”

Mr Francois spent eight months held hostage in Syria with Foley, mostly in underground cells with no natural light.

For two-and-a-half months, Mr Francois was chained to fellow French hostages Nicolas Henin, Edouard Elias, and Pierre Torres. Mr Francois said he had never spoken publicly about Mr Foley or Mr Sotloff before because of threats of reprisals.

Mr Henin also paid tribute to Mr Foley, saying: “James was a very good friend and a great support. He was always there when you were feeling not so well with some kind words. He managed to make seven months of captivity easier.”

Mr Henin, however, was sceptical about reports that a group of British jihadists nicknamed “The Beatles” were the prime culprits. “If investigators were to go in that direction, they would be misleading themselves,” he said.

Jeroen Oerlemans, a Dutch journalist who was held hostage in Syria with a British colleague, John Cantlie, for nine days last year before the two men were freed, said Foley had worked tirelessly trying to secure their release.

He said: “The colleague with whom I was abducted was good friends with James. When we missed our appointment with him, somewhere in Syria, alarm bells immediately went off for Foley. He pulled back across the border to Turkey, and put all his journalistic contacts gathering information on us.”

When the two men were freed by opposition forces, he said: “James was the first to hug me. I did not know him, but because he had been so closely involved with our liberation he knew me well.”

Mr Oerlemans decided Syria was too dangerous to return to, saying: “You must know very well who you go into business with, your contacts must be one hundred per cent reliable. And even then, James was hugely experienced and had those contacts. Yet it happened to him.”